Anyway, I think that whether or not we should be sending messages to ETs is possibly a moot point.
For over 100 years Earth has been a beacon of electromagnetic radiation leaking out into space. There's an ever expanding sphere (currently about ~100 light years radius) where ETs could pick up our signals and deduce they're obviously from an intelligent source, and try to make sense of them. On the other hand, maybe the signals will have become so diluted they will be indistinguishable from background noise.
I also wouldn't put much stock into what Stephen Hawking says, not because he's not a brilliantly intelligent man, but because like a lot of brilliant men, he's a world class expert in a narrow field of knowledge - quantum physics and cosmology - and thus doesn't necessarily have the knowledge of other subjects to make earth shattering proclamations about them. It's not that he's right or wrong, he's just another in a long line of people who are famous or experts in one field, making proclamations about fields they don't really know that much about.
Edited by Archimedes, 23 June 2011 - 03:13 PM.